Just to close off the electronics failure thing..........Quite often I hear that a part has been changed many times, each time the problem goes away, and the part fails again. 2x 3x, is very suspicious and requires more scrutiny. Sometimes the real fault is disturbed in the replacement process and the problem seems fixed....for a while, because the problem was not originally corrected.
One story I have if you have the time,.....of course you do you are on the forum anyway......
Years ago I worked at Motorola Automotive in the charging systems group. We provided charging systems for AMC, Volkswagen, agriculture machinery, etc. The VW bug used our alternators at the time.
One time we heard from VW America that our alternators were burning up in VW bugs. This is obviously strange because they go thru tons of testing, design verification, etc. before going into high volume production.
Anyway we found some customer in Kansas City had her alternator changed several times for that reason. Management bought the customer a new car, the dealer's mechanic put in a fresh alternator, and it was driven back to our facility near Chicago. No failure.
We then used an engineering test alternator (wired with thermocouples) and went driving the car thru many different driving profiles, while monitoring temperatures. No joy, temps were fine, no observed failures.
Knowing the alternator was changed before the trip to our lab we started to think of what could have possibly changed.
To those who have never seen a VW bug alt or gen, it has a double-ended shaft, the drive pulley is on one end and the back end mounts the engine fan. There is a plate arrangement on the back end that bolts to the alt body which also seals the engine fan in the fan housing. The plate mounts on two bolts on the alt back housing, the bolts are 180 degrees apart. I noticed that there is a duct area towards one edge of the plate but not the other. I suggested we try to put the plate on 180 degrees out to see what would happen.
The plate bolted on, added the fan, installed the alt assembly onto the engine, and ran in in the lab garage with full electrical load. 5 minutes later, it started pumping smoke.
It turns out the duct portion of the plate needs to be on the bottom of the fan housing because that's a high pressure area which forces air thru the alt for cooling. No cooling air, alt burns up. Apparently the KC mechanic installed the plate correctly, whereas the previous alt changes had the plate installed incorrectly causing multiple comebacks.
VW changed the plate to add a slot for a locating screw we added to the alt rear housing.
Long story, but an example of changing parts, not finding nor fixing the root cause.
George